This invention relates to a preventive and curative preparation for thrombosis, which comprises as an active component thereof sitosterol or fucosterol which is a plant sterol containing an ethyl or ethylidene group at the 24-position, and a method of treating thrombosis.
Thrombosis causes blood to undergo localized coagulation into thrombi in blood vessels or cardiac cavities in a living body, whereby to develop circulation troubles and thus to cause serious diseases such as cerebral apoplexy and myocardial infraction. As a factor taking part in the formation of thrombi, there is an acceleration in coagulability of blood. This acceleration is observed together with increased blood platelets, enhanced aggregability of blood platelets, increased concentrations of various coagulation factors, decreased concentrations of anti-coagulation factors and of fibrinolytic substances, and so on. For the prevention and treatment of thrombosis, heparin and coumarin derivatives have been used as drugs for reducing the coagulability of blood. Besides, preparations of enzymes having plasminogen-activating effects, such as urokinase, streptokinase and the like, have been developed in recent years as thrombus resolvents which can positively dissolve thrombi and can thus improve the flow of blood. These conventional preparations are however accompanied by such problems as strong antigenicity, high pyrogenicity and short-lasting effectiveness.
Taking a hint from the fact that in the activation of fibrinolytic substances for dissolution of thrombi, plasmin which serves to solubilize fibrin is formed as a result of an action of a plasminogen-activating substance produced by vascular endothelial cells on plasminogen, the present inventor has carried out an extensive investigation on substances which may accelerate the formation of plasminogen-activating substances. As a result, it has been found that a great deal of a plasminogen-activating substance may be released from vascular endothelial cells in the presence of a plant sterol of a certain type, such as sitosterol and fucosterol, leading to completion of this invention.
Sitosterol has ever been used as an anticholesteremic as disclosed in, e.g., Chemical Abstract Vol. 82 (1975) 175227z and Chemical Abstact Vol. 93 (1980) 54004t. However, the present inventor is the first to have discovered that the sitosterol and the fucosterol or an ester of these are useful for treatment of thrombosis.